A light-emitting-diode (“LED”) lamp (also known as a bulb or, more generally, an LED lighting product) may be used to replace an incandescent, halogen, or other bulb; the LED lamp provides the same or similar light while consuming less power. The LED lamp includes at least one LED, support circuitry to drive the LED (such as a transformer, dimmer, LED driver, and/or other circuit components), lenses, and support/housing structures. The LED lamp may be used in many different kinds of fixtures, each having different heat dissipation rates. For example, a recessed-ceiling fixture may be extensively insulated and therefore have a high ambient temperature. Designers of LED lamps cannot predict the type of fixture with which the LED lamp will be used and therefore may include thermal protection mechanisms (also known as thermal-foldback circuits) to monitor the temperature of the lamp and automatically reduce the LED drive current when the temperature becomes too high. The reduction in drive current causes the LED lamp to draw less power and generate less heat, thereby preventing the bulb from overheating and prolonging the lifespan of the LEDs therein.
There is, however, a drawback to this approach. Dimmers have minimum hold current requirements, as do the electronic low-voltage transformers commonly used in lighting systems, in order to function properly. The thermal-foldback circuits described above, when engaged, cause an LED lamp to draw less current. If the current drawn by the LED lamp drops too far, it may fall below the hold current required by the dimmer and/or electronic transformer. At that point, the dimmer and/or electronic transformer may no longer function properly, causing flickering of the lamp due to intermittent delivery of power from those upstream components.